N

1. Nannoplankton, 819

2. Nansen water bottle, 353, 354

   1. used for collecting phytoplankton, 382

3. Nathansohn's theory of plant nutrient distribution, 784

4. Nekton, 281, 810–812

   1. biological factors in movements of, 904–907

5. Nemertinea, synopsis of, 307

6. Neon, 189

7. Nereocystis:

   1. reproduction, 292

   2. structure, 292

8. Neritic environmental province, 275, 279, 784

9. Nets, plankton, 376

   1. catching power, 378–379

   2. operation, 380

   3. types, 379

10. Nitrate:

    1. distribution in basins, 245

    2. distribution in oceans, 241–243

       1. related to deep-water circulation, 754

    3. factors influencing distribution, 246

    4. produced on sea bottom, 995

    5. reduction and denitrification, 915

    ---

    ― 1070 ―

    6. regeneration, 254–257

    7. seasonal variation, 252, 253

    8. utilization as a measure of production, 932

11. Nitrate-nitrogen, ratio to phosphate-phosphorus, 236, 243

12. Nitrite:

    1. distribution in oceans, 243

    2. produced on sea bottom, 995

13. Nitrogen, 181

    1. compounds, utilization of by plants, 768

       1. in see water, 252–225

          1. seasonal variation, 252

          2. transformations, 253–255

    2. dissolved:

       1. amounts in sea water, 188

       2. determination, 187

       3. solubility, 188–191

    3. in sediments, 1010, 1011

14. Nitrogen cycle, 913–916

    1. ammonification, 914

    2. in the sea, 255–257

    3. nitrification, 914

    4. nitrogen assimilation, 915

15. Nitrogen fixation, 916

16. Nitrogen-phosphorus ratio in plankton, 236, 768

17. Nitzschia clasterium, 296, 769

    1. photosynthesis, 781, 933

18. Noctiluca, 304

    1. reproduction, 319

19. Normal Water, 51

20. North Atlantic Current, 673, 680–683

21. North Atlantic Ocean:

    1. currents, 671–686

    2. oxygen distribution, 686

    3. water masses, 668–671

22. North Equatorial Current:

    1. Atlantic, 671

    2. Indian Ocean, 696

    3. Pacific, 708, 709, 718, 719

23. North Pacific Current, 719, 722

24. North Pacific Ocean:

    1. currents, 718–728

    2. eastern gyral, 723, 724

    3. oxygen distribution, 728–730, 753

    4. water masses, 712–718

25. North Polar Sea:

    1. bottom topography, 30–32

    2. currents, 661

    3. oxygen content, 662, 663

    4. water masses, 658, 659

26. North Sea:

    1. currents, 660

    2. water masses, 657

27. Norwegian Current, 659, 660

    1. fluctuations, 655, 661, 662

28. Norwegian Sea:

    1. bottom topography, 30–32

    2. currents, 659

    3. inflow of water, 652–656

    4. outflow of water, 652–656

    5. oxygen content, 662

    6. water masses, 656, 657

29. Nursery areas, 315

30. Nutritional relationships, 882–898

    1. micro-animals, significance of, 884–886

    2. micro-plants, significance of, 883